大兴安岭寒温带地区森林流域溪流水化学特征

Hydrochemical Characteristics of Streams of Forest Watershed in Cold-temperate Zone of Greater Xing'an Mountains,China

选取大兴安岭北部4个典型森林小流域研究其溪流水化学特征。结果表明,大兴安岭北部森林小流域溪流多为弱碱性极低矿化度极软水,除大马场溪流外,pH值均在7.17-8.07之间,TDS在49-129mg/L之间,总硬度在47.83-52.18mg/L之间,水质很好。老爷岭北麓森林流域溪流中NO-3和K＋含量高于南麓溪流,分别相差1.73倍和0.97倍,Fe和Mn含量则低于南麓溪流,分别相差15.41倍和2.25倍,北麓溪流Pb2＋和Mn含量的变化幅度大于南麓溪流,北麓溪流2种化学成分的变异系数分别为124.11%-210.14%和138.41%-160.79%,南麓则分别为90.79%-105.82%和57.63%-94.63%。树种组成对溪流水化学特征有一定影响,TDS、总硬度、F-、Cl-、Fe含量变化幅度均表现出针叶树比例大的流域大于针叶树比例小的流域,说明阔叶树种对稳定地表径流中的化学成分有一定的积极作用。溪流中K＋、Ca2＋、Na＋、Mg2＋、SO2-4、F-、Fe相对雨水为淋失型迁移,而Cl-、NO-3、Zn2＋、Pb2＋为内贮型迁移,Mn的移动趋势不明显。

Four typical forest watersheds in the north of Greater Xing＇an Mountains were selected to study the hydrochemical characteristics of streams.The results showed that the water of most streams of forest watershed in the north of Greater Xing＇an Mountains were weak alkaline,extremely low salinity and highly soft.The water pH value ranged from 7.17to 8.07,the TDS ranged from 49mg/L to 129mg/L,and the total hardness ranged from 47.83mg/L to 52.18mg/L for all but Da Machang Stream,which was a very good water quality.The NO3 and K＋content of the streams in the north of Laoye Mountains were higher than that in the south,which magnitudes of difference were 1.73 times and 0.97 times respectively.The Fe and Mn content of the streams in the north were lower than that in the south by magnitudes of 15.41 times and 2.25 times respectively.The variations of Pb2＋and Mn of the streams in the north were more obvious than that in the south.The coefficients of variation of two chemical compositions in the north ranged from 124.11% to 210.14% and 138.41% to 160.79% respectively,while they ranged from 90.79% to 105.82% and 57.63% to 94.63% respectively in the south.Species composition also had some influence on the chemical compositions of stream water.The variations of TDS,total hardness,F-,Cl-and Fe of the watersheds with more coniferous trees were all more obvious than that in the watersheds with fewer coniferous trees,which showed that broad leaved trees played a positive role in stabling chemical composition of surface runoff.Compared to those of the precipitation,the migration types of K＋,Ca2＋,Na＋,Mg2＋,SO24,Fand Fe were leaching,while that of Cl-,NO3,Zn2＋ and Pb2＋ were storage.The migration trend of Mn was not obvious.